Nice video.
I don't believe that a taper is necessary on the nozzle. It should be accurate enough without.
I agree that it is not necessary to have a good seal. My Yamaha P&P "leaks" (by design) all over the place.
As to the nozzles and magnets. You need to make sure that the nozzle tip is not magnetised. Otherwise the chip components will tick to the nozzle.
Cheers,
Peter.